Undefeated heavyweight contender Anthony Joshua has 15 knockouts yn ei 15 ymladd proffesiynol. Check out this video compilation from SHOWTIME Sports showcasing all of Joshua’s KOs. And tune in dydd Sadwrn to watch the 2012 British Olympic Gold Medalist challenge undefeated American titlist Charles Martin for the IBF Heavyweight World Championship, byw ar Showtime yn 5 p.m. A/2 p.m. PT from The O2 in London.